Here is an exhibition the like of which I have never seen. Nor in the near future are we likely to see anything quite as grand. The show at the Palazzo Strozzi, Florence (until 23 January) features more than 70 paintings by Bronzino – his real name was Agnolo di Cosimo di Mariano – a butcher's son who became the Medicis' favourite artist. Museums from Budapest to Los Angeles, have loaned works, and there are two recent discoveries: a dwarf, finally unveiled, and a crucified Christ. The identity of the second item had been in doubt for over a century. But the art historian Philippe Costamagna and Carlo Falciani, one of the exhibition's curators, have established that it is by Bronzino.

The dwarf, Braccio di Bartolo, was a familiar figure at the Medici court. He was nicknamed Morgante, after the giant in a poem by Luigi Pulci. Bronzino did a painting of him, front and back, using both sides of the canvas. He was naked, but for a moth fluttering in front of his genitals. This was subsequently thought to be shocking and the offending parts were painted over with vine leaves, leading people to suppose he was the satyr Silenus. Restored for the present show, the painting has recovered its original meaning: seen from the front, he is preparing to go bird catching; and from behind, we see him proudly brandishing his catch. Carrying on an old quarrel, Bronzino is suggesting that painting is a superior art form to sculpture, capable not only of representing a subject from several angles but also of showing the passing of time.

Bronzino was an exceptional painter, contributing with others such Hans Holbein the Younger to defining the style of court portraits in Europe. But he was a thinker and a poet too, though the exhibition does not deal with either in depth. This may be due to modern prudishness, for some of his texts revel in the ribaldry that distinguished the 16th century.

His paintings are more restrained, though as the British critic Andrew Graham-Dixon points out, "John Ruskin positively hated the artist's creations", terrified by the sexual undertones of his mythological compositions.

Art historians in general have tended to disregard him too. He was overshadowed by Michelangelo and Raphael, almost his contemporaries, and Mannerism, of which he was a leading exponent, soon fell out of favour. Showing off their technical skill, painters twisted bodies into impossible positions and added garish colours. But to contemporary viewers, they probably just looked sumptuous, in keeping with the court of Cosimo de Medici, who restored art to its rightful place after Savonarola had condemned it as futile.

The exhibition shows all this. The presentation is clear, with exhibits placed in chronological order, and then by theme. It is instructive too, particularly the details accompanying each work, which are set out on a double-page in large characters on a little lectern. Nor does this obstruct our view of the paintings, which thoroughly deserve lengthy consideration, sometimes revealing amusing details: a grotesque figure carved into the arm of a chair, or a Klein-blue antique sculpture standing on a table. Here is another figure, maybe representing [the biblical] Susanna bathing, just next to the hand of a lute player, yet another instance of Bronzino's efforts to show that painting can represent all the arts, including poetry. His open books are legible, for those of us with good eyesight and a grasp of Italian.

Lastly the Uffizi gallery has loaned about 30 of its Bronzinos, it being impossible to move the others, in particular the frescoes and a few canvases that are simply too large. The exhibition is consequently a good opportunity to look at various other Florentine sights, such as the chapel of Eleonora of Toledo – Cosimo's wife – at Palazzo Vecchio, for the Christ in Limbo at Santa Croce church, or the basilica of San Lorenzo for the Martyrdom of Saint Lawrence.